Background: Lung transplant recipients (LTR) have the highest risk of CMV infection. CMV pneumonitis, lymphocytic bronchitis, and detection of CMV DNA in bronchoalveolar lavage fluid are independent risk factors for the development of chronic lung allograft dysfunction (CLAD). However, to demonstrate the clinical impact of the indirect effects of CMV, it is necessary to conduct studies with a very large sample size.

Hypothesis: The different current preventive strategies for CMV infection in LTR and their clinical application on a daily basis impact on the development of direct and indirect effects of CMV in this population.

Objectives: To study the effect of CMV infection on LTR in relation to current preventive strategies in terms of:

• The incidence of acute and chronic rejection
• The incidence of other opportunistic infections
• The incidence of neoplastic disease, especially, post-transplant lymphoproliferative disease
• Patient and graft survival Methods: Multicenter, retrospective, cohort study. Consecutive inclusion of all adult lung transplant recipients from 2013 to 2017 with 2 years of follow-up. The investigators will collect and analyze the main clinical and microbiological variables in order to respond to the objectives of the study.

Relevance: Knowing in detail the current epidemiology of CMV infection in LTR and its subsequent influence on both mortality and the presence of different complications, could allow improving the management of these patients in the future.

Inclusion Criteria:

· Survival > 1 month post-transplant

• High to moderate risk patients to develop CMV disease by means of pre-transplant CMV serology:

• Donor positive to recipient negative
• Recipient positive independently of donor serology

Exclusion Criteria:

• Survival < 1 month after procedure
• Low risk serology to develop CMV disease: both donor and recipient seronegative

All those LTR performed in Spain during the study period